If you don't have a graphixcard then I'd say grabb it. It gives you a few more screenmodes/colordepths. Result in programs that use more colors or can use custom screens with own color settings (such as DeluxePaint and other paint programs aswell as DOpus) will also gain more screenmodes/colordepths to play with.
But if I where you I'd concider saving the money for a graphixcard instead.
